There are various types of mobile radio networks with which mobile related services can be provided to mobile nodes. For example, Global System for Mobiles (GSM) networks provides a facility for data and voice communications via fixed capacity radio communications channels. The Universal Mobile Telecommunications System (UMTS) on the other hand provides improved flexibility in affording greater data rates to mobile nodes whilst still providing a facility for mobile communications made possible by a cellular architecture. On the other hand the Wireless Local Area Networks (WLAN) standards for example IEEE 802.11B referred to as WIFI provide a facility for high data rate communications within so called WLAN hotspots. Such WLANs provide a substantially greater data rate than can be provided through cellular mobile radio architectures such as GPRS and UMTS. Furthermore, WLANs are often unregulated in that a single mobile node can occupy a greater proportion of the available data communications bandwidth than another mobile node.
Many applications utilize an internet protocol to support data communication such as for example multi-media services. As such, a communications service may be provided by communicating internet protocol packets via a variety of different networks. The application may not be aware of the type of network via which the internet protocol packets are being communicated. Thus, in the case of wireless communications the application may communicate internet packets via GPRS or WLAN networks. However, since these different types of mobile radio networks offer substantially different communications bandwidths, a quality of service which can be supported will be different in accordance with the communications bandwidth provided by the mobile access network. As such, a communications service may be provided using different communications session levels, each level providing a different quality of service as determined by the access network via which the mobile node is currently communicating. For each communications session level, different types of media may be communicated. Thus for example, for one communications session level video may be supported, whereas another level may only support audio.
European patent EP 1 435 748 discloses a telecommunications system in which a mobility manager is arranged to control a communications session provided to a mobile node in accordance with an access network which the mobile node is currently communicating internet data packets. An applications server provides a communications service to the mobile nodes. The mobility manager in combination with the applications server negotiate a change in a communications session level within the service which is provided to the mobile node in accordance with a change in communications bandwidth associated with a change of affiliation from one access network to another access network. In accordance with a relative change in the communications bandwidth available between the first mobile network and the second mobile network, a change in the quality of service provided via the communications session may be affected thereby maintaining a level of service to which a user has subscribed.
International patent application WO 03/047296 discloses an arrangement in which messages which form part of a mobile IPV6 internet protocol are extended to provide a facility for a mobile node and a mobility manager to communicate link quality related messages. In particular, the mobile node is disclosed as sending a request for a handover only when the link quality on its current communications mobile access network is decreasing, so that, seamless mobility is achieved but no quality of service is enabled.
International patent application WO 04/017395 discloses a traffic shaper which is operable to control an amount of bandwidth available from an access point, which is used by different traffic types and protocols.